1. Field of the Invention:
This invention relates to an amorphous metal film, and a method and apparatus for production thereof.
2. Description of the Related Art:
Amorphous materials are not entirely crystalline and have only short-range order in its structure, having characteristics good in corrosion resistance, wear resistance, etc.
Further, amorphous iron or iron alloy has a good magnetic characteristic, such as a high magnetic permeability and a low coercive force, so that materials suitable for use in various kinds of applied art such as transformers and magnetic heads are provided. Consequently, researches and studies have in recent years been made on amorphous materials.
Heretofore, for forming amorphous materials such as an amorphous film, a vacuum deposition method, a sputtering method and a liquid quenching method are known.
In the vacuum deposition method, a sample is heated and evaporated in a vacuum chamber by, for example, a heater, and is deposited and cooled on a substrate to form an amorphous film.
In the sputtering method, a plasma of argon or nitrogen gas is formed in a vacuum chamber to sputter (strike out) sample particles with the plasma particles so that the sample particles are deposited and cooled on a substrate.
In the liquid quenching method, a sample is melted by heating at a temperature higher than its melting point, and the melted sample is then cooled quickly.
However, according to the liquid quenching method, there is a limit in the cooling rate (maximum speed of about 10.sup.7 K/sec), and hence only limited kinds of metals or alloys can be made amorphous.
According to the vacuum deposition method, since the energy of the sample particles during deposition is relatively low, the cooling rate of the sample particles deposited on the substrate is small so that only limited kinds of metals or alloys can be made amorphous.
According to the sputtering method, the cooling rate of the sample particles on the substrate is higher than that in the vacuum deposition method, but argon gas in the atmosphere will be mixed into a prospective film during sputtering, thus deteriorating the film quality. Therefore it is difficult to form a good quality amorphous film. Forming a single-metal or alloy amorphous film requires a high cooling rate of, for example, higher than 10.sup.10 K/sec for Ni (nickel) [Publication by H. A. Davies: proc. of 3rd intern. conf. on Rapidly Quenched Metals (1978) 1]. For this reason, according to the conventional methods, such good quality amorphous film could not be achieved.